Heavy duty switch with magnetic blasting



Jan. 27, 1959 o. BARDORF HEAVY DUTY SWITCH WITH MAGNETIC BLASTING Filed Dec. 18, 1956 ATTORNEYS nited HEAVY DUTY SWITCH WITH MAGNETIC BLASTING Application December 18, 1956, Serial No. 629,014

Claims priority, application Switzerland December 19, 1955 3 Claims. (Cl. 200-446) My invention relates generally to heavy duty switches with magnetic blasting and more particularly to a heavy duty switch having a structure which allows easy accessibility of the movable parts without a reduction of the dynamic strength of the closing forces created by the load current.

Heavy duty switches with magnetic blasting are generally equipped with main switch contacts and spark drawing contacts. It is important that the spark drawing contacts receive proper switching operation. The arcs created between the contact elements upon disconnection of the switch will be drawn in length'by the magnetic blasting and will be cooled, subdivided, and extinguished in the spark arrester. The main contacts on the other hand must disconnect the entire load current without the generation of switching currents therein. Accordingly the main contacts must be opened earlier and closed later than the spark drawing contacts. The main contacts must also be so operated that the heating thereof will not be too great, resulting in insuflicient cooperation of the contact pieces and undesirable increase of contact resistance. The main contacts must also be so operated that the contact pressure is always strong and the contact resistance remains as small as possible. Moreover, it is appropriate that the contacts be overhauled for repair from time to time. In order that these objects might be achieved, two requirements are necessary which are not always met by the known types of switches of the prior art. First, it is necessary to avoid a reduction of the dynamic forces of the current loop in the supply line and, secondly, it is necessary that the main switch contacts be readily accessible. The avoidance of the dynamic forces by means of suitable control of the supply line and suitable arrangement of the switch contacts is well known in the prior art. By means of the instant invention means are provided for avoiding these extensive dynamic forces. The accessibility of the contacts is possible in known types of apparatus only through separately constructed measures. The structural parts must be made to be situated in front of the contacts to be easily accessible. To move the contacts, in the known types of apparatus, in the direction of the operating linkage, it is always necessary to remove certain structural parts in order to be able to reach the contacts. This repair necessitates loss of valuable operating time.

According to the instant invention, the movable contact elements of the main contacts are arranged on the opposite side of the switch from the driving mechanism, and open in the direction away from the drive mechanism. The main contacts are so designed that the dynamic force of the current tends to close the contacts. The spark drawing contacts on the other hand are caused to open in a direction toward the operating mechanism as in the known devices.

The movable contacts are thus arranged on the rear side of the switch. No wider construction parts lie before it so that it may be removed and exchanged without supplementary operating mechanism. The movable rates. atent contact element can be fastened on the operating system from the rear of the switch.

By this arrangement the dynamic forces are so directed as to compress the contacts. These forces could be enlarged in this manner so that the contacts in the supply leads could be disconnected to prevent a large current loop.

Other objects and advantages of my invention will become more apparent from a study of the following specification when considered in conjunction with the accompanying drawing.

Referring to the figure, the movable spark drawing contact 1 and the fixed spark drawing contact 2 are arranged within a suitable spark chamber 3. The movable main contact 4 as illustrated bridges the stationary contacts 5, 5', although the contacts could also be arranged with only a single interruption point. The current travels from the connector lead 6, which might be constructed as a connecting plug or clip, through the bus bar 7, the main contacts 5 and 4, the bus bar 8 to another connector lead 9. In parallel with the main contacts are connected the spark drawing contacts through the bus bar 10 carrying the fixed contact element 2, through the movable contact piece 1 positioned on the lever 12 pivotally mounted about pivot point 11, and through the bus bar 13. The current flowing through the main contacts forms a curved path which seeks to traverse the contact element 4. Moreover the contact element 4 is so formed that a current loop arises therein as signified by the dashed line 14 having the tendency to close the contacts.

The actuation of the contacts is caused by the release shaft 15; as shown in the figure, disconnection of the switch will be effected by movement of the shaft 15 to the right. The link 16 causes the rotatable lever 12 to pivot about the pivot point 11 with the result that the spark drawing contacts are opened. Similarly the link 17 secured to the lever 12 is actuated to open the main contacts. The contact element 4 is thus readily accessible and detachable from the rear of the switch. The contact element 4 may be removed from the lever 17 merely by loosening the bolt 18. The entire arrangement is so designed that the length of the contact path of the spark drawing contacts is greater than the length of the contact path of the main contacts as a result of the pivotal movement of the lever 12. This is accomplished by making the length of the arm of lever 12 connected to the spark drawing contacts greater than the length of the arm of lever 12 connected to the main contacts.

By this arrangement a simple construction is created which makes possible a definite contact pressure in the main contacts owing to the dynamic force of the traversing current and at the same time readily allows accessibility and removability of the movable contact element 4.

While in accordance with the provisions of the statutes I have illustrated and described the best form of my invention known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus described without departing from the spirit of my invention as set forth in the appended claims.

I claim:

1. In a heavy duty switch having spaced fixed main contacts, fixed and movable spark drawing contacts on one side of said fixed main contacts; a movable main contact on the other side of said fixed main contacts, said movable main contact being so formed that the dynamic force of the current through the main contacts tends to close the movable contact on the fixed main contacts, and driving means on the same side of said fixed main contacts as said spark drawing contacts for moving the movable spark drawing contact and the movable main contact in opposite directions laterally away from thefixed main contacts during opening of the switch.

2. In a heavy duty switch having spaced fixed main contacts, fixed and movable spark drawing contacts on one side of said fixed main contacts, and a magnetic blasting chamber associated with said spark-drawing contacts; a movable main contact on the other sidetof said fixed main contacts, said movable main contact being so formed that the dynamic force of current'through the main contacts tends to close the movable contact on the fixed main contacts, driving means on the same side of said fixed main contacts as said spark drawing contacts, and means on said other side of said fixed main contacts removably securing said movable contact to said driving means so that said movable main contact is readily exchangeable from' said other side of the fixed contacts, said driving means actuating the movable sparkdrawing contact and the movable main contact in opposite directions away from the fixed main contacts during opening of the switch.

3. In a heavy duty switch having spaced fixed main contacts, fixed and movable spark drawing contacts on one side of said fixed main contacts, and a magnetic blasting chamber associated with said spark drawing; contacts; a movable main contact on the other side of said fixed main contacts, said movable main contact being so formed that the dynamic force of current through the main contacts tends to close the movable contact on the fixed main contacts, and driving means on the same 4 side of said fixed main contacts as said spark drawing contacts actuating the movable spark drawing contact and the movable main contact in opposite directions away from the fixed main contacts during opening of the switch, said driving means including a two-armed lever pivotally mounted on a fixed pivot intermediate its ends and connected at one end to said movable spark drawing contact and at the other end to said movable main contact, the arm of said lever connected to the movable main contact being shorter than the armconnected to said spark drawing contact so that the spark drawing contact covers a greater path of travel than the main contact during opening of the switch.

References Citedin the file of this patent UNETED STATES PATENTS 470,161 Wurtz Mar. 1, 1892 789,975 Hertz May 16, 1905 1,645,905 Gregory Oct. 18, 1927 2,243,038 Ludwig May- 20, 1941 2,323,642 Baker July 6, 1943 2,328,318 Wood Aug. 31, 1943 2,443,521 Scott June 15, 1948 2,477,189 Lerstup July 26, 1949 FORElGN PATENTS 273,895. Germany May 11,1914 666,982 France June3, 1929 270,864 Italy Ian. 22, 1930 696,410 Germany Sept. 20, 1940 

